Hooking up system for bridged mono subs

[Dubravac]

Just need general help in how to connect to my crossover. I running my tops througj one amp in parallel. I'd like to run my bass bins in bridged mono, so one bass bin to one bridged amplifier. Using two 218 bass bins. How do i connect that to my dbx223?? Thank alot!!

[RoadRanger]

What particular 218 bass bin and amp?

[heath_eld]

You connect the low outputs to the amp inputs. It sounds like your whole system is mono so perhaps you're only using one side of the crossover. If you were mixing stereo the dbx 223 has a "mono sum" mode. Or do you mean that you have 2 amps both bridged?

 

In that case you would use the crossover in stereo and the subs connected one amp to each side. Why are you parallelling your tops??

 

Note: i have deliberately refrained from buying into the "don't bridge you'll blow up your subs" debate. I am sure others will comment.

[RoadRanger]

Note: i have deliberately refrained from buying into the "don't bridge you'll blow up your subs" debate. I am sure others will comment.

Nothing wrong with bridging a 800 or 1400 watt amp into a couple higher end sub drivers - hence my asking him what he has before "unloading" .

[Dubravac]

Yes, i have two plx3602s. Running one of them in parallel to each sub (so ch1 to one sub and ch2 to the other sub) just doesnt give me enough low output. I have an extra plx3602, so id like to bridge both and run each sub to its own plx3602. So just trying to get some info on how to connect that to my crossover (dbx223).

 

Second question, do i have to adjust anything with my speakon cables? I have two nl4fx's that i run to the subs currently.

 

Thx guys!

[monkeyland]

what model sub

[tlbonehead]

Yes, i have two plx3602s. Running one of them in parallel to each sub (so ch1 to one sub and ch2 to the other sub) just doesnt give me enough low output. I have an extra plx3602, so id like to bridge both and run each sub to its own plx3602. So just trying to get some info on how to connect that to my crossover (dbx223). Second question, do i have to adjust anything with my speakon cables? I have two nl4fx's that i run to the subs currently. Thx guys!

so, my wards garden tractor won't pull a 6 bottom plow. Should I install a 454 in it? Is that kinda what you are asking?

[Coaster]

 

so, my wards garden tractor won't pull a 6 bottom plow. Should I install a 454 in it? Is that kinda what you are asking?

 

 

slant 6 has smoother torque, you may get better traction with the smaller engine.

[RoadRanger]

Yes, i have two plx3602s. Running one of them in parallel to each sub (so ch1 to one sub and ch2 to the other sub) just doesnt give me enough low output.

Are you pushing them into the limiters now or are you a "clip limiter lights should never flicker" type of guy? Assuming they are decent bins there's no reason you can't push them 3-6db into the limiters - definitely try that before resorting to bridging (which will probably destroy them in short order with 3x the power ).

[Dubravac]

The subs are EV QRX 218's ... dual 18" subs.

 

Like i said, running them in parallel through one QSC PLX3602 is just not giving me the low end i'm looking for. It's either i bridge the two amps i got or buy something like a RMX5050 to power them. The RMS of the subs is 1200W, and the PLX is a 1200W amp per channel, but it's just not giving me enough.

[RoadRanger]

Again, are you driving them fully or not letting the clip limiters flicker? That amp into them should be able to cover 300+ people unless something is very wrong.

[Dubravac]

Yes, they are ok for 300+ coverage type of venues ... little adjustment on the low end output gain on the crossover, and it works out well ... problem is when we play much bigger venues that seat 600+ people. Just don't get the low end. I've read on this board as well as others that people have the same problem getting the QRX218's going with only 1200W. Most recommend between 1800-2200W. I'm open to suggestions.

 

Is it possible to daisy chain them together ?? If bridged one PLX3602 (which would have 3600W) ... can i run one speakon cable to one bin, then a cable from that bin to other bin ?? I know people daisy chain they're tops and bins together, just wondering if it can be done bass bins ?? 3600W divided by the two bass bins would give them each 1800W, which might be a bit better ... ? ...

 

RoadRanger, no i don't drive them to clip, in all honesty ... from my last gig, which was a 700 seated venue ... i cranked my input gain on the crossover to +5 and the low end gain to +10. Still didn't seem that i could really get punchy low end from them. I asked a local sound engineer that i kind of know and he said guaranteed, your bins are being underpowered. I'm not a pro, just a weekend gigger. So i really appreciate all your opinions and help.

 

heath_eld ... sorry just read your post above. Not sure why i shouldn't be running my tops in parallel to be honest. They sound perfectly fine the way they are connected to be honest. Run them in parallel through a RMX2450 (750W) and they are clear and get really loud with no problems. My bass bins at the moment, not so much haha ...

 

Many thanks guys !!

[RoadRanger]

 

RoadRanger, no i don't drive them to clip, in all honesty

You should really try bringing them up to the clip limiter lights flashing and then 6 db past that before you conclude they can't do the job. That's about at the point that the bottom end will start to "pump" audibly but you'll figure it out on your system.

I asked a local sound engineer that i kind of know and he said guaranteed, your bins are being underpowered.

Is he gonna pay to have your subs reconed? For 350-700 you should really have another pair of them subs with the other PLX driving them. Sorry but there just isn't any substitute for more subs. If running what you have into the limiters (I assume your amp gains are wide open?) doesn't do it more power into them is just gonna get expensive.

 

I couldn't quite figure out what you have for tops but the general rule with R&R is to have two sub drivers per top - if you have four tops it's silly not to have four 2x18 subs to keep up with them.

[gspointer]

Can you rent another pair for the big gigs? If not, you will probably be happier and save money in the long run by buying another pair of subs.

[Dubravac]

2 tops ... 2 subs ... tops are qrx212's, subs are qrx218s. Having 4 bins wouldn't be possible for us to lug around. Don't have the room. Do you think powering the 218's with a QSC PL380 would be safe and adequate ?

[Vinny D]

I owned the QRX218 sub, it really will pay off for you to either get the EV processor (or a Driverack 260) and have someone SMAART your system.

Or....You can use the settings that came from my rig as a starting point.

 

HighPass: 30hz LR24DB

LowPass: 80hz LR24DB

EQ: 40HZ +6db, Q4.0

65HZ -3db, Q5.0

Peak Voltage: 130v, .01 attack, 1.0 release

RMS Power: 600w @ 4ohms, 6.0 release

 

 

Those settings loaded into a Crown Itech8000 brought my QRX218s to life, they benefit greatly from the crossover slope and the BIG EQ boost at 40hz.

With the testing I had done with that sub it was very easily apparent that the QRX218s will NEVER be able to handle anywhere near it's PEAK power rating (4800w).

The driver starts to bottom out WAY before it will ever see anything near that.

That sub really only needs 12-1800w MAXIMUM to drive it to it's full potential.

 

Before changing your amp you really should get a system processor (Must be the EV DC1, or Driverack 260) so you can load the crossover and EQ settings, then the advantage is you will be able to properly LIMIT how much power goes to the sub to keep it safe.

[tlbonehead]

slant 6 has smoother torque, you may get better traction with the smaller engine.

Good thought. Slant-6 lasts forever and HP would be more in relation to available traction.

[Vinny D]

 

2 tops ... 2 subs ... tops are qrx212's, subs are qrx218s.

 

Buy the EV processor....

[Unalaska]

Any more than 200-300 people I'd rent a second pair of subs, more power will just get wasted as heat and destroy those drivers prematurely. 1200w into each cab is perfect, if they are properly highpassed/limited then 1600w would be the limit IMHO. But what you need is more cones, nothing more than that. You could even power them with the amps you have now (2ohm/ch) but recommended would be a 2nd set of amps.

[RoadRanger]

BTW do you cluster the subs together? That can give you a bit more impact too. Dual 12 tops need a pair of 2x18 to keep up with each I'm afraid. If you commonly cluster you might make do with just 3. If yous guys are commonly doing 500+ rooms you should be able to afford the proper transport for four subs! What are your subs high pass filtered at? If presently below 40Hz try 40Hz - it will free up a bit of wasted power for more punch. Oh, and the difference between running the subs never flickering the clip lights and instead pushing 6 db into them is potentially the same as increasing your amp power by 4x - try it, really...

 

EDIT> and as Vinny implied - an iTech amp has the best limiters around if you really want to get the most out of your subs. An iTech 4000 can get to almost the 130V peak he was using (126.5 theoretically) so should work just as well as the 8000.

[agedhorse]

Looking closely at the EV driver displacement models in the QRX-218, they begin to displacement limit at around 800-1000 watts at 35Hz, so with the 40Hz boost (don't know if that came from EV or from somebody guessing), the mechanical limitation is going to be a very real issue.

 

From my experience with this product (I've reconed a lot of these drivers), I would suggest the following a s a good, safe starting point:

 

HighPass: 34hz BW24DB

LowPass: 90hz LR24DB

Peak Voltage: 100v, 0.01 attack, 0.2 release (Crown)

RMS Power: 800w @ 4ohms, 3.0 release

 

Otherwise, choose an amp of around 1200 watts RMS per channel and the above parameters. If this won't do it, you need more speaker to go along with more power.

 

These are reasonably expensive drivers to recone.

[RoadRanger]

We're in "SMAART" territory here - their offices are a 15 minute walk from my place. They do a great job with flattening out a system and getting the time delays between tops and subs right but I disagree than getting the subs flat down to their lower limits is a good idea if you're gonna be powering things up to the limit . I'd just dial in that 6db boost for the break music (assuming you run the system lower for that than during the "live" portion) and dial it out when at full boogie. I do that all the time with whatever subs I happen to be using as I tend to use subs that drop off at 50Hz.

 

Oh, and for the mathematically challenged that 100V peak = 1250W peak each driver which is what a 1200wrms/ch@4ohm amp will give you.

[Vinny D]

 

Looking closely at the EV driver displacement models in the QRX-218, they begin to displacement limit at around 800-1000 watts at 35Hz, so with the 40Hz boost (don't know if that came from EV or from somebody guessing), the mechanical limitation is going to be a very real issue. .

 

 

What we found when running my QRX218 through SMAART was that the spec. sheets EV provides on that cabinet don't even come close what the actual output of that sub.

In order for it to get even close it needed that big boost down at 40hz.

With how we had the limiting setup (in testing) we were driving the snot out of my rig and were watching and listening to the driver very closely.

I would have really had to screw up bad when I was running it with a live band to damage the drivers.

 

I can say, when we were done with setting my system up and I used those settings out in the real world the subs (and system) sounded the best it ever had.

Which is why my suggestion still holds, skip buying a new amp, buy the EV processor seeing how the OP has a complete EV QRX rig.

[agedhorse]

Well Vinny, using the LR HPF set at 30Hz is already 6dB down at 30Hz and about 4.5dB down at 40Hz, so you were in effect working around a poor choice of HPF... inj effect making 2 wrongs a kinda right.

 

Smaart gives data, it doesn't think nor does it check the choices made. If you used a 32Hz BW HPF, your 40Hz eq would be very different... maybe not even necessary.

 

There's a lot more to the details behind the simple user interface that makes for good speaker tunings. Understanding the fundamentals of how the filters work, and how they interact with the acoustic properties of the speaker and the environment are not rrivial. Unfortunately there are a lot of folks falling back on Smaart and other analysis programs rather than understanding the basics. To me, using an LR filter alignment for a HPF is kind of a bone-head mistake. There are exceptions, but they fall under very rare and specific situations of which this is not one IMO.

[RoadRanger]

LR HPF only makes sense if you're crossing over to another box lower. And as I implied boosting at or close to your HPF is just defeating the HPF's effectiveness at excursion control. I'd switch to a 36 or 48 db per octave BW tuned a bit lower before resorting to a boost (except at low SPL's as I said). Some of these DSP's have dynamic EQ but I think setting that properly is beyond most folk's abilities. I think most of the SMAART folks are used to tuning huge install rigs with lots of headroom where boosting down low isn't an issue. I disagree with their methodology for smaller portable rigs run close to their limits.

 

But not to lose sight of the OP I don't think anybody thinks a pair of 2x18 are gonna comfortably cover 700 people for a rock concert?

 

BTW I have the chance to take a SMAART class in a couple weeks but don't think I'm ready to drink the kool-aid .